Mr Hilsenteger presents the Unbox Therapy channel on YouTube, which has more than 12 million subscribers.

In a video published on Saturday, he tested nine iPhones by plugging them into an official Apple power supply.

Image copyrightYouTube/Unbox Therapy

While the 2017 iPhone X charged without problem, many of the new XS and XS Max phones refused to charge when plugged in.

Most of the phones would charge only when the display was activated to wake up the device. However, one of them would not charge at all.

Mr Hilsenteger said he had been alerted to the problem when a viewer had emailed him describing their troubles.

He had not noticed the issue himself because he used wireless charging rather than the power cable on his device.

"Responding to those people on a platform like this should bring light to it and hopefully some sort of software fix, if possible," he said in the video.

"This is my job. I have to call this stuff out. I have to hold these companies accountable."

Several complaints about the XS and XS Max failing to charge have also been posted on Apple's discussion forum on its website.

Complaints can also be found on social media, where some people have described being unable to charge their phone at all once the battery is exhausted.

Some users have speculated that the problem is related to a recent change in Apple's security settings.

Since iOS 11.4.1 was released, the lightning port on iPhones can be disabled when the phone has been idle for a while. That could stop thieves, cyber-attackers or law enforcement officers accessing it.

"In some cases, it might not charge," the company advises on its website.

However, that does not explain why more iPhone XS and XS Max users are facing the issue.